This project involves the use of ionizing radiation to graft certain monomers to the plastic parts of extracorporeal blood circulation equipment such as membrane oxygenators. Each monomer grafted will bear a chemical grouping capable of reacting with and linking to heparin. The grafted plastic parts will then be treated with heparin, or a selected heparin fraction, resulting in the chemical bonding of heparin to the plastic parts, and rendering the plastic parts thromboresistant. A detailed study of the results should yield a better understanding of the antithrombogenic effect of heparin.